A CSPRNG is surely a type of PRNG. Is that not right?
Their comment doesn't really seem correct to me. The title is "Cracking random number generators (xoroshiro128+)" which seems pretty accurate to me. The article definitely doesn't seem to say it's breaking anything other than a very specific, flawed random number generator.
I'm not in this field, but I know enough to know what not to do (most of the time).
PRNGs produce numbers that seem hard to predict. CSPRNGs product numbers that actually are hard to predict, assuming P != NP (kind of).
Yes. In the same way the POTUS limousine is a car
Edit: thinking a bit more about it. I guess it wouldn't make sense to call anything "crypto" in crypto. It's like calling fries "french fries" in France. There they're just fries. I know this is a bad example because french fries are probably not from France :o)
This is critical for performance-sensitive operations. For example, certain audio and video codecs need to simulate noise. In these cases, high performance is much more important than cryptographic security.
Which makes stuff like PCG even weirder! Because in most cases, what you want is a somewhat slower generator that has better failsafe behavior.
This is made worse by many purchasing decisions made based upon microbenchmarks with the requirements of "default settings" so defaulting to insecure is a sound business decision in more cases than you might think.
But I stand by my argument that the default platform RNG should be a CSPRNG, and that developers should reach for a CSPRNG by default.
Which makes all the attention we've been giving to stuff like xoroshiro128+ and PCG pretty confusing to me. It feels like people arguing very earnestly about non-problems, while ignoring a huge problem in our standard libraries.
PCG is cryptographically secure, though. Or at least, it is as cryptographically secure as any other PRNG in the sense that nobody actually knows how to predict it, many have tried, nobody has succeeded, but nobody has proved it impossible.
Cryptographic generators don't work like PCG and xoroshiro and Mersenne Twister. They're generally built by taking a cryptographically secure cipher or hash core, "keying" it with secret entropy, and running it in a streaming configuration (like CTR mode).
A properly designed CSPRNG can only be "cracked" in a few specific scenarios:
1. The primitive it's built on (or the streaming construction it's configured in) is broken, in which case the news for cryptography as a field is significantly bigger than the fact that an RNG has a flaw.
2. An attacker has exploited a systems flaw to directly disclose the contents of the memory the CSPRNG is operating out of, in which case you have bigger problems than your CSPRNG.
3. The secrets that key the generator have become predictable. This is in practice the only way CSPRNGs get broken (unintentionally), and, in practice, always means the CSPRNG wasn't initialized properly (the "cold start entropy problem").
You should use the getrandom() system call, or read from /dev/urandom, to the exclusion of all other mechanisms.